Re: [Xen-devel] [PATCH v2 03/11] IOMMU/MMU: enhance the call trees of IOMMU unmapping and mapping

["Jan Beulich" <jbeulich@xxxxxxxx>]

>>> "Xu, Quan" <quan.xu@xxxxxxxxx> 04/20/16 7:29 AM >>>
>I am still not sure whether we really need throw out error message for each 
>IOMMU mapping or not.
>If yes, I will throw out error message for each IOMMU mapping in next v3.

Ideally not, if it's a batch that it failing, The question just is whether at 
the point you
issue the error message you can know another got already emitted. In no case
must this lead to spamming of the console originating from an unprivileged 
domain.

>> > +                    if ( unlikely(ret) )
>> > +                    {
>> > +                        while (i)
>> > +                            iommu_unmap_page(d, gfn + --i);
>> 
>> How about below?
>> 
>> while (i-- >= 0)
>>      iommu_unmap_page(d, gfn + i);
> 
>this modification is based on discussion rooted at 
>http://lists.xenproject.org/archives/html/xen-devel/2016-03/msg01779.html
>wait for Jan's decision.

But did you really _follow_ that discussion? The adjustment done by that patch
was specifically not deemed good, so the shape Kevin suggests is in line with
the outcome of that discussion (except that I'd suggest omitting the ">= 0", the
more that i at least ought to be unsigned here).

Jan


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